The present invention relates to address resolution in an asynchronous transfer mode (ATM) communications network. When deploying ATM networks, network providers must deal with the recent proliferation of ATM address types and formats. A network provider has to decide on the type of ATM address to be deployed in its own network, under the influence of administrative, technical, and other factors. For example, ATM End System Addresses (AESAs) may be deployed in some private and public networks because of the difficulty in obtaining native E.164 addresses. For some of the public carriers, native E.164 addresses may be chosen since they already own them. The notion of "public" and "private" is blurred in ATM networks--even so-called "public" ATM networks have segregated address domains that are very different from the traditional telephony public network.
In addition to the different administrative aspects, various addresses are also involved directly with a variety of signaling protocols and routing algorithms. For example, the ATM Forum Private Network-Network Interface (P-NNI) routing protocol runs on the structure of 20 bytes AESA, whereas Broadband ISDN User's Part (B-ISUP) signaling was originally based on native E.164.
One approach to the problem of address resolution has been to use only native E.164 address in public ATM networks, assuming that every public network can route on native E.164. As for connections between public networks and private networks, private networks translate the Network Service Access Point (NSAP) formatted address into a native E.164 address for the public network to route on. Some public networks, however, use NSAP addresses instead of native E.164 addresses. Further, this approach cannot handle number portability issues, and does not provide the internal/external address separation for public carriers. Another approach--resolution based on interface type--is also limited since different network providers may opt for different interfaces and signaling messages to connect networks. These limitations render the prior approaches to address resolution unacceptable.
It is desirable, therefore, to provide an end-to-end address resolution scheme sensitive to the related signaling and routing protocols involved in order to set up connections across different ATM network addressing domains. As yet, no ATM standards provide a complete mechanism adequate for address planning and interworking, which is imperative for ATM networks to scale and interconnect.
It is also desirable to provide a generic end-to-end address resolution scheme applicable to all signaling protocols (e.g., ATM Forum v. ITU-T standards, DSS2 (Digital Signal System #2)-based v. B-ISUP-based protocols) at all different types of ATM standard interfaces to achieve complete ATM network interconnection. It would also be desirable for such a generic scheme to allow ATM switches to handle address interworking without changing the control software for every specific application or interface, for example where one network uses ATM Forum P-NNI and another uses ITU-T B-ISUP.